In the Sky This Week – April 21, 2020

I lost my brother Victor to COVID-19 on April 12th. Please, everyone take precautions and stay safe!

The triple-planet conjunction of Mars, Jupiter and Saturn continues in the southeastern predawn sky.

Conjunction of Saturn, Mars and Jupiter in the southeastern predawn sky this week. Credit: Stellarium / Bob Trembley.

Venus, Aldebaran and Rigel form a temporary triangle asterism in the western sky at dusk. The Moon appears near Aldebaran on the evening of April 25th, and near Venus the next evening.

The star Vega and the constellation Lyra appear above the northeastern horizon at midnight.

The star Vega and the constellation Lyra above the northeastern horizon at midnight this week. Credit: Stellarium / Bob Trembley.

The Moon is a waning crescent, visible low to the east before sunrise.

The new Moon occurs on April 23rd.

After April 23rd, the Moon will be a waxing crescent, visible toward the southwest in early evening.

The Moon from 2020-04-21 – 2020-04-27. Visualizations by Ernie Wright / NASA’s Scientific Visualization Studio.

Moon News

The Sun has been spot-free for 16 days. Coronal holes appear at both poles – the southern coronal hole has been open and huge for several weeks.

The Sun seen in 193 angstroms (extreme ultraviolet) Apr. 20, 2020:

Light prominence activity on the Sun’s limb over the last couple days – but enough to get a good pic!

The Sun seen in 304 angstroms (extreme ultraviolet) Apr. 20, 2020:

Facebook: SolarActivity

https://www.facebook.com/photo.php?fbid=10219713612704574&set=gm.3137746356236687&type=3&theater&ifg=1

Solar Corona

Solar wind speed is 406.8 km/sec (↑), with a density of 5.7 protons/cm³ (↑↑) at 1136 UT.

Near real-time animation of the corona and solar wind from the Solar & Heliospheric Observatory (SOHO):

Animated LASCO C2 Coronograph showing the solar corona above the Sun’s limb (the white circle). Credit: NASA/JPL-Caltech-SOHO

Sun News

Upcoming Earth-asteroid encounters:

Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. Red highlighted entries are asteroids that either pass very close, or very large with high relative velocities to the Earth. Table from SpaceWeather.com

On Apr. 19, 2020, the NASA All Sky Fireball Network reported 4 fireballs. 
(4 sporadics)

In this diagram of the inner solar system, all of the fireball orbits intersect at a single point–Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). Credit: SpaceWeather.com

Fireball & Meteor News:

Position of the planets and a couple spacecraft in the inner solar system.

Position of the planets and a couple spacecraft in the inner solar system, 2020-04-21. Credit: NASA Eyes on the Solar System / Bob Trembley.

I don’t believe I’ve ever posted a zoom-in to Earth showing several satellites using NASA’s Eyes – so here ‘ya go:

Position of the planets in the middle solar system.

Position of the planets in the middle solar system, 2020-04-21. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets some transneptunian objects in the outer solar system – the orbit of TNO Makemake highlighted.

Position of the planets in the outer solar system, 2020-04-21, with the orbit of TNO Makemake highlighted. Credit: NASA Eyes on the Solar System / Bob Trembley.

OSIRIS-REx Asteroid Sample Return Mission

Hubble Space Telescope

Chandra Space Telescope

International Space Station

Earth Day

ex·o·plan·et /ˈeksōˌplanət/, noun: a planet orbiting a star other than the Sun.

Data from the NASA Exoplanet Archive
* Confirmed Planets Discovered by TESS refers to the number planets that have been published in the refereed astronomical literature.
* TESS Project Candidates refers to the total number of transit-like events that appear to be astrophysical in origin, including false positives as identified by the TESS Project.
* TESS Project Candidates Yet To Be Confirmed refers to the number of TESS Project Candidates that have not yet been dispositioned as a Confirmed Planet or False Positive.

SGR A* – The Milky Way’s Central Black Hole

I was playing around in SpaceEngine, and found one of the stars that orbits really close to SGR A* – the Milky Way’s central black hole. I took this screen shot when the star S175 was at periapsis (closest-approach) with SGR A*. I’m pretty sure the radiation environment here is fantastically hostile.

Artist’s concept of star S175 seen near periapsis with SGR A*. Credit: SpaceEngine / Bob Trembley

The Local Stellar Neighborhood

Continuing with my visual tour of nearby stars and their systems, we travel to Ross 128, 11 light years distant.

Distance to Ross 128 from Sol; the plane (green) is aligned with the orientation of the plane of the Milky Way galaxy. Credit: SpaceEngine / Bob Trembley.

Ross 128

Ross 128 is a red dwarf in the equatorial zodiac constellation of Virgo, near β Virginis. The apparent magnitude of Ross 128 is 11.13, which is too faint to be seen with the unaided eye. Based upon parallax measurements, the distance of this star from Earth is 11.007 light-years (3.375 parsecs), making it the twelfth closest stellar system to the Solar System. It was first cataloged in 1926 by American astronomer Frank Elmore Ross.

This low mass star has a stellar classification of M4 V, which places it among the category of stars known as red dwarfs. It has 15% of the mass of the Sun and 21% of the Sun’s radius, but generates energy so slowly that it has only 0.033% of the Sun’s visible luminosity; however, most of the energy being radiated by the star is in the infrared band, with the bolometric luminosity being equal to 0.36% of solar. This energy is being radiated from the star’s outer atmosphere at an effective temperature of 3,180 K. This gives it the cool orange-red glow of an M-type star.

Ross 128 is an old disk star, which means it has a low abundance of elements other than hydrogen and helium, what astronomers term the star’s metallicity, and it orbits near the plane of the Milky Way galaxy. The star lacks a strong excess of infrared radiation. An infrared excess is usually an indicator of a dust ring in orbit around the star.– Wikipedia

Ross 128 system architecture. Credit: SpaceEngine / Bob Trembley.

Ross 128 b

Ross 128 b was discovered in July 2017 by the HARPS instrument at the La Silla Observatory in Chile, by measuring changes in radial velocity of the host star. Its existence was confirmed on 15 November 2017. It is the second-closest known Earth-size exoplanet, after Proxima b. It is calculated that Ross 128 b has a minimum mass of 1.35 times the Earth, and orbits 20 times closer to its star than Earth orbits the Sun, intercepting only about 1.38 times more solar radiation than Earth, increasing the chance of retaining an atmosphere over a geological timescale. Ross 128 b is a closely orbiting planet, with a year (rotation period) lasting about 9.9 days. At that close distance from its host star, the planet is most likely tidally locked, meaning that one side of the planet would have eternal daylight and the other would be in darkness. Near-infrared high-resolution spectra from APOGEE have demonstrated that Ross 128 has near solar metallicity; Ross 128 b therefore most likely contains rock and iron. Furthermore, recent models generated with these data support the conclusion that Ross 128 b is a “temperate exoplanet in the inner edge of the habitable zone.” – Wikipedia

Artist’s concept of exoplanet Ross 128b. SpaceEngine / Bob Trembley

Stay safe, be well, and look up!

Apps used for this post:

NASA Eyes on the Solar System: an immersive 3D solar system and space mission simulator – free for the PC /MAC. I maintain the unofficial NASA Eyes Facebook page.
Stellarium: a free open source planetarium app for PC/MAC/Linux. It’s a great tool for planning observing sessions. A web-based version of Stellarium is also available.
Universe Sandbox: a space simulator that merges real-time gravity, climate, collision, and material interactions to reveal the beauty of our universe and the fragility of our planet. Includes VR support.
SpaceEngine: a free 3D Universe Simulator for Windows. Steam version with VR support available.

Section header image credits:
The Sky – Stellarium / Bob Trembley
Observing Target – Turn Left at Orion / M. Skirvin
The Moon – NASA/JPL-Caltech
The Sun – NASA/JPL-Caltech
Asteroids – NASA/JPL-Caltech
Fireballs – Credited to YouTube
Comets – Comet P/Halley, March 8, 1986, W. Liller
The Solar System – NASA Eyes on the Solar System / Bob Trembley
Spacecraft News – NASA Eyes on the Solar System / Bob Trembley
Exoplanets – Space Engine / Bob Trembley
Light Pollution – NASA’s Black Marble
The Universe – Universe Today